Stented transcatheter prosthetic heart valve delivery system and method

ABSTRACT

A percutaneous stented valve delivery device including an inner shaft, a sheath, and a delivery capsule. The sheath slidably receives the inner shaft. A capsule proximal zone is attached to the sheath. A capsule distal zone is configured to transition between normal and flared states. A diameter of the distal zone is greater in the flared state, and the capsule includes a shape memory component that naturally assumes the normal state. The device is operable to perform a reversible partial deployment procedure in which a portion of the prosthesis is exposed distal the capsule and allowed to radially expand. Subsequently, with distal advancement of the capsule, the distal zone transitions to the flared state and imparts a collapsing force onto the prosthesis, causing the prosthesis to radially collapse and become recaptured within the delivery capsule. The capsule can include a laser cut tube encapsulated by a polymer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.12/886,975, filed Sep. 21, 2010, entitled “STENTED TRANSCATHETERPROSTHETIC HEART VALVE DELIVERY SYSTEM AND METHOD”, that claims priorityunder 35 U.S.C. §119(e)(1) to U.S. Provisional Patent Application Ser.No. 61/244,344, filed Sep. 21, 2009, entitled “Stented TranscatheterProsthetic Heart Valve Delivery System and Method”, and bearing AttorneyDocket No. M190.347.101/P0035222.00; the entire teachings of which areincorporated herein by reference.

BACKGROUND

The present disclosure relates to systems, devices, and methods forpercutaneous implantation of a heart valve prosthesis. Moreparticularly, it relates to systems, devices, and methods fortranscatheter implantation of a stented prosthetic heart valve,including partial deployment, recapturing and repositioning of theprosthesis at the implantation site.

Diseased or otherwise deficient heart valves can be repaired or replacedwith an implanted prosthetic heart valve. The terms “repair” and“replace” are used interchangeably throughout the specification, and areference to “repair” of a defective native heart valve is inclusive ofa prosthetic heart valve that renders the native leafletsnon-functional, or that leaves the native leaflets intact andfunctional. Conventionally, heart valve replacement surgery is anopen-heart procedure conducted under general anesthesia, during whichthe heart is stopped and blood flow is controlled by a heart-lung bypassmachine. Traditional open surgery inflicts significant patient traumaand discomfort, and exposes the patient to a number of potential risks,such as infection, stroke, renal failure, and adverse effects associatedwith the use of the heart-lung bypass machine, for example.

Due to the drawbacks of open-heart surgical procedures, there has beenan increased interest in minimally invasive and percutaneous replacementof cardiac valves. With percutaneous transcatheter (or transluminal)techniques, a valve prosthesis is compacted for delivery in a catheterand then advanced, for example, through an opening in the femoral arteryand through the descending aorta to the heart, where the prosthesis isthen deployed in the annulus of the valve to be restored (e.g., theaortic valve annulus). Although transcatheter techniques have attainedwidespread acceptance with respect to the delivery of conventionalstents to restore vessel patency, only mixed results have been realizedwith percutaneous delivery of the more complex prosthetic heart valve.

Various types and configurations of prosthetic heart valves areavailable for percutaneous valve replacement procedures, and continue tobe refined. The actual shape and configuration of any particularprosthetic heart valve is dependent to some extent upon the native shapeand size of the valve being repaired (i.e., mitral valve, tricuspidvalve, aortic valve, or pulmonary valve). In general, prosthetic heartvalve designs attempt to replicate the functions of the valve beingreplaced and thus will include valve leaflet-like structures. With abioprostheses construction, the replacement valve may include a valvedvein segment that is mounted in some manner within an expandable stentframe to make a valved stent (or “stented prosthetic heart valve”). Formany percutaneous delivery and implantation devices, the stent frame ofthe valved stent is made of a self-expanding material and construction.With these devices, the valved stent is crimped down to a desired sizeand held in that compressed arrangement within an outer sheath, forexample. Retracting the sheath from the valved stent allows the stent toself-expand to a larger diameter, such as when the valved stent is in adesired position within a patient. In other percutaneous implantationdevices, the valved stent can be initially provided in an expanded oruncrimped condition, then crimped or compressed on a balloon portion ofcatheter until it is as close to the diameter of the catheter aspossible. Once delivered to the implantation site, the balloon ininflated to deploy the prosthesis. With either of these types ofpercutaneous stented prosthetic heart valve delivery devices,conventional sewing of the prosthetic heart valve to the patient'snative tissue is typically not necessary.

It is imperative that the stented prosthetic heart valve be accuratelylocated relative to the native annulus immediately prior to fulldeployment from the catheter as successful implantation requires theprosthetic heart valve intimately lodge and seal against the nativeannulus. If the prosthesis is incorrectly positioned relative to thenative annulus, serious complications can result as the deployed devicecan leak and may even dislodge from the native valve implantation site.As a point of reference, this same concern does not arise in the contextof other vascular stents; with these procedures, if the target site is“missed,” another stent is simply deployed to “make-up” the difference.

While imaging technology can be employed as part of the implantationprocedure to assist a clinician in better evaluating a location of thetranscatheter prosthetic heart valve immediately prior to deployment, inmany instances, this evaluation alone is insufficient. Instead,clinicians desire the ability to partially deploy the prosthesis,evaluate a position relative to the native annulus, and then repositionthe prosthesis prior to full deployment if deemed necessary.Repositioning, in turn, requires the prosthesis first be re-compressedand re-located back within the outer delivery sheath. Stated otherwise,the partially deployed stented prosthetic heart valve must be“recaptured” by the delivery device, and in particular within the outersheath. While, in theory, the recapturing of a partially deployedstented prosthetic heart valve is straight forward, in actual practice,the constraints presented by the implantation site and the stented heartvalve itself render the technique exceedingly difficult.

For example, the stented heart valve is purposefully designed to rigidlyresist collapsing forces once deployed to properly anchor itself in theanatomy of the heart. Thus, the delivery device component (e.g., outerdelivery sheath) employed to force a partially-deployed segment of theprosthesis back to a collapsed arrangement must be capable of exerting asignificant radial force. Conversely, however, the component cannot beoverly rigid so as to avoid damaging the transcatheter heart valve aspart of a recapturing procedure. Along these same lines, the aortic archmust be traversed, necessitating that the delivery device providesufficient articulation attributes. Unfortunately, existing deliverydevices do not consider, let alone optimally address, these and otherissues.

As mentioned above, an outer sheath or catheter is conventionallyemployed to deliver a self-deploying vascular stent. Applying this sametechnique for the delivery of a self-deploying stented prosthetic heartvalve, the high radial expansion force associated with the prosthesis isnot problematic for complete deployment as the outer sheath is simplyretracted in tension to allow the prosthetic heart valve to deploy. Werethe conventional delivery device operated to only partially withdraw theouter sheath relative to the prosthesis, only the so-exposed distalregion of the prosthetic would expand while the proximal region remainedcoupled to the delivery device. In theory, the outer sheath could simplybe advanced distally to recapture the expanded region. Unfortunately,with conventional sheath configurations, attempting to compress theexpanded region of the stented prosthetic heart valve by distallysliding the sheath is unlikely to be successful. The conventionaldelivery sheath cannot readily overcome the radial force of the expandedregion of the prosthesis because, in effect, the sheath is placed intocompression and will collapse due at least in part to the abrupt edge ofthe sheath being unable to cleanly slide over the expanded region of theprosthesis. This effect is illustrated in a simplified form in FIGS.1A-1C. Prior to deployment (FIG. 1A), the stented prosthetic heart valveP is constrained within, and supports, the sheath S. With deployment(FIG. 1B), the sheath S is distally retracted, and the prosthesis Ppartially deploys. Were an attempt made to “recapture” the prosthesis Pby distally sliding the sheath (FIG. 1C), a leading end E of the sheathS would abruptly abut against the enlarged diameter of the prosthesis P,such that the distal end E cannot readily slide over the prosthesis P.Further, the sheath S is no longer internally supported and the radiallyexpanded bias of the prosthesis P will cause the sheath S to buckle orcollapse.

Another concern presented by stented heart valve in situ recapturing isinfolding. Infolding is defined as the prosthetic heart valve (and inparticular the stent frame) folding into itself during the resheathingprocess. Basically, if the sheath or catheter component utilized toeffectuate resheathing is overtly rigid (longitudinal) at the distalend, an excessive crimping force is applied; due to possible inherentcell instability of the stent frame, a section of the stent frame mayfold non-uniformly, resulting in stent folding into itself. For example,FIGS. 2A-2D are simplified end views (e.g., inflow end) of a stentedprosthetic heart valve P being resheathed or transitioned from a naturalor expanded arrangement (FIG. 2A) to a contracted arrangement (FIG. 2D).As shown, during the stages of recapture, a cell section C of the valvestent frame P collapses non-uniformly, folding into itself. Infoldingmay damage the stent frame, decrease full deployment predictability,etc.

In light of the above, a need exists for a stented transcatheterprosthetic heart valve delivery system, device, and method thatsatisfies the constraints associated with heart valve implantation andpermits partial deployment and recapturing of the prosthesis.

SUMMARY

Some aspects in accordance with principles of the present disclosurerelate to a delivery device for percutaneously deploying a stentedprosthetic heart valve. The device includes an inner shaft assembly, asheath, and a tubular delivery capsule. The inner shaft assembly definesa distal tip, a proximal end, and an intermediate portion providing acoupling structure configured to selectively engage a stented prostheticheart valve. The sheath forms a lumen sized to slidably receive at leastthe intermediate portion of the inner shaft, and terminates at a distalregion. The tubular delivery capsule is formed separately from thesheath and define a proximal zone and a distal zone. The proximal zoneis attached to the distal region of the sheath. The distal zoneterminates at a distal end, and is configured to transition between anormal or relaxed state and a flared state. A diameter of the distal endis greater in the flared state than in the normal state. Further, thecapsule includes a shape memory component constructed to naturallyassume the normal state. With this construction, the device isconfigured to slidably receive a stented prosthetic heat valve withinthe delivery capsule and is operable to perform a reversible partialdeployment procedure in which a portion of the stented prosthetic heartvalve is exposed distal the capsule and allowed to radially expand.Subsequently, with distal advancement of the capsule relative to theprosthesis, the distal zone transitions to the flared state and impartsa collapsing force onto the prosthesis, causing the prosthesis toradially collapse. In some embodiments, the capsule includes a laser cuttube encapsulated by a polymer. In related embodiments, the laser cuttube forms an intermediate zone exhibiting elevated radial flexibilityas compared to at least the distal zone, and optionally forms opposinglongitudinal spines providing columnar strength.

Yet other aspects in accordance with principles of the presentdisclosure relate to a method of deploying a stented heart valveprosthesis to an implantation site. The method includes removablyloading a stented heart valve prosthesis to a delivery device. Thedelivery device includes an inner shaft, a sheath, and a tubulardelivery capsule. The delivery capsule has a proximal zone attached toand extending from a distal region of the sheath, as well as a distalzone opposite the proximal zone. Further, the prosthesis is coupled tothe inner shaft and is slidably received within the delivery capsulesuch that the delivery device retains the prosthesis in a collapsedarrangement. The stented heart valve prosthesis is delivered, in thecollapsed arrangement, through a bodily lumen and to the implantationsite via the delivery device. The delivery capsule is proximallyretracted relative to the prosthesis such that a distal portion of theprosthesis is exposed distal the capsule. In this regard, the distalportion self-expands toward a normal or expanded arrangement and atleast a proximal portion of the stented prosthetic heart valve isretained within the delivery device in the collapsed state. A positionof the prosthesis relative the implantation site is evaluated. Undercircumstances where the evaluation indicates that the prosthesis is notcorrectly positioned, the sheath and the delivery capsule are distallyadvanced relative to the prosthesis. In this regard, the distal zonecircumferentially flares about the stented heart valve prosthesis withthe distal movement while simultaneously imparting a collapsing forceonto a contacted region of the prosthesis, causing the contacted regionto transition toward the collapsed arrangement. Finally, the deliverycapsule is fully proximally retracted from the prosthesis such that theprosthesis deploys from the inner shaft. In some embodiments, flaring ofthe distal zone reduces retraction forces and instability, and providessufficient axial strength so as to not buckle during the recapture step.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C are simplified side views illustrating deficiencies ofexisting stent delivery sheaths or catheters to effectuate recapture ofa partially deployed stented prosthetic heart valve;

FIGS. 2A-2D are simplified end views of a stent frame of a stentedprosthetic heart valve undergoing recapture and experiencing infolding;

FIG. 3 is a simplified cross-sectional view of a transcatheter heartvalve repair system in accordance with principles of the presentdisclosure, including a delivery device and a stented prosthetic heartvalve;

FIG. 4A is a side view of a stented prosthetic heart valve useful withsystems and methods of the present disclosure and in a normal, expandedarrangement;

FIG. 4B is a side view of the prosthetic heart valve of FIG. 4A in acompressed arrangement;

FIG. 5A is a side view of a tube portion of a delivery capsule componentof the delivery device of FIG. 2, including a distal zone in a normal orrelaxed state;

FIG. 5B is a side view of the tube of FIG. 5A and including the distalzone in a flared state and an intermediate zone in a flexed condition;

FIG. 5C is an enlarged two-dimensional or unwrapped representation ofthe tube of FIG. 5A;

FIG. 5D is a perspective view of a portion of an alternative tube usefulwith the delivery capsule of FIG. 3;

FIG. 6 is an enlarged two-dimensional or unwrapped view of a distalportion of the tube of FIG. 5A;

FIG. 7 is a cross-sectional view of the delivery capsule of FIG. 3;

FIG. 8 is a graph comparing retraction forces experienced by a deliverycapsule incorporating a flarable distal zone in accordance withprinciples of the present disclosure as compared to a conventionalsheath or catheter;

FIG. 9 is an exploded view of a delivery device useful with the systemof FIG. 3;

FIG. 10 is a transverse, cross-sectional view of an optional deliverysheath useful with the delivery device of FIG. 9;

FIG. 11A is a cross-sectional view of a portion of a heart valvereplacement system in accordance with the present disclosure, includingthe delivery device of FIG. 9 loaded with the prosthetic heart valve ofFIG. 4B;

FIG. 11B is a side view of the heart valve replacement system of FIG.11A;

FIGS. 12A-16 illustrate use of the system of FIG. 3 in delivering astented prosthetic heart valve to an implantation site, includingpartial deployment and recapturing of the prosthesis;

FIG. 17A is a side view of alternative tube useful with the deliverycapsule component of the device of FIG. 3 and in a natural or unflaredstate;

FIG. 17B is a perspective view of the tube of FIG. 17A in a flaredstate;

FIG. 17C is a perspective view of the tube of FIG. 17A in an articulatedor flexed orientation;

FIG. 18A is a side view of another tube useful with the delivery capsuleof FIG. 3 and in a normal or unflared state;

FIG. 18B is a side view of the tube of FIG. 18A in a flared state;

FIG. 18C is a side view of the tube of FIG. 18A in an expanded state;

FIG. 19A is a perspective view of a portion of an alternative tubeuseful with the delivery capsule of FIG. 3; and

FIG. 19B is a perspective view of the tube of FIG. 19A upon finalassembly.

DETAILED DESCRIPTION

Current transcatheter valve delivery systems do not have the capabilityof transcatheter valve re-positioning in the antegrade or retrogradedirections after partial deployment. The delivery devices and systems ofthe present disclosure overcome these problems, and permit the clinicianto partially deploy the transcatheter valve, and prior to full release,recapture and reposition or remove it. In general terms, the devicesfunction by reducing the peak forces required to recapture the stentedprosthesis, while at the same time increasing the axial strength andbuckling resistance of the device component utilized to effectuaterecapture.

With the above in mind, FIG. 3 illustrates, in simplified form, oneembodiment of a heart valve repair system 18. The system 18 generallyincludes a delivery device 20 and a stented prosthetic heart valve 22.As a point of reference, FIG. 3 illustrates a loaded state of the system18 in which the stented heart valve prosthesis 22 is compressed andloaded within the delivery device 20. The delivery device 20 includes aninner shaft assembly 24, a sheath assembly 26, a delivery capsule 28,and a handle 30 (referenced generally). Details on the variouscomponents are provided below. In general terms, however, the innershaft assembly 24 is slidably received within a portion of the sheathassembly 26 and the delivery capsule 28, and is configured forreleasable coupling with the prosthesis 22. The delivery capsule 28extends distally from, or is provided as part of, the sheath assembly26, and is configured to permit partial and complete deployment of theprosthesis 22 from the loaded state of the system 18 (e.g., FIG. 3), aswell as to recapture the prosthesis 22 following partial deployment. Byincorporating a shape memory (e.g., Nitinol) structure into the deliverycapsule 28, a portion of the delivery capsule 28 is allowed to expandcircumferentially or flare at a distal end thereof when encountering theoutward radial forces (or resistance to radial compression) of thetranscatheter valve prosthesis 22 during deployment and recapture. Theexpanded structure reduces the peak forces required to collapse thecells of a stent frame of the prosthesis 22 by redistributing thepotential energy along a length of the expanded flare. In someembodiments, the delivery capsule 28 further incorporate features thatimpart non-kinking flexibility. This flexible or articulatable regionallows the delivery capsule 28 to orient itself in, for example, theaortic arch, thereby reducing the retraction force required forrecapturing the prosthesis 22 along a bend.

As referred to herein, stented transcatheter prosthetic heart valvesuseful with and/or as part of the various systems, devices, and methodsof the present disclosure may assume a wide variety of differentconfigurations, such as a bioprosthetic heart valve having tissueleaflets or a synthetic heart valve having polymeric, metallic, ortissue-engineered leaflets, and can be specifically configured forreplacing any heart valve. Thus, the stented prosthetic heart valveuseful with the systems, devices, and methods of the present disclosurecan be generally used for replacement of a native aortic, mitral,pulmonic, or tricuspid valve, for use as a venous valve, or to replace afailed bioprosthesis, such as in the area of an aortic valve or mitralvalve, for example.

In general terms, the stented prosthetic heart valves of the presentdisclosure include a stent or stent frame maintaining a valve structure(tissue or synthetic), with the stent having a normal, expandedarrangement and collapsible to a compressed arrangement for loadingwithin a delivery device. The stent is normally constructed toself-deploy or self-expand when released from the delivery device. Forexample, the stented prosthetic heart valve useful with the presentdisclosure can be a prosthetic valve sold under the trade nameCoreValve® available from Medtronic CoreValve, LLC. Other non-limitingexamples of transcatheter heart valve prostheses useful with systems,devices, and methods of the present disclosure are described in U.S.Publication Nos. 2006/0265056; 2007/0239266; and 2007/0239269, theteachings of each which are incorporated herein by reference. The stentsor stent frames are support structures that comprise a number of strutsor wire portions arranged relative to each other to provide a desiredcompressibility and strength to the prosthetic heart valve. In generalterms, the stents or stent frames of the present disclosure aregenerally tubular support structures having an internal area in whichvalve structure leaflets will be secured. The leaflets can be formedfrom a variety of materials, such as autologous tissue, xenographmaterial, or synthetics as are known in the art. The leaflets may beprovided as a homogenous, biological valve structure, such as porcine,bovine, or equine valves. Alternatively, the leaflets can be providedindependent of one another (e.g., bovine or equine pericardial leaflets)and subsequently assembled to the support structure of the stent frame.In another alternative, the stent frame and leaflets can be fabricatedat the same time, such as may be accomplished using high-strengthnano-manufactured NiTi films produced at Advance BioProsthetic Surfaces(ABPS), for example. The stent frame support structures are generallyconfigured to accommodate at least two (typically three) leaflets;however, stented prosthetic heart valves of the types described hereincan incorporate more or less than three leaflets.

Some embodiments of the stent frames can be a series of wires or wiresegments arranged such that they are capable of self-transitioning fromthe compressed or collapsed arrangement to the normal, radially expandedarrangement. In some constructions, a number of individual wirescomprising the stent frame support structure can be formed of a metal orother material. These wires are arranged in such a way that the stentframe support structure allows for folding or compressing or crimping tothe compressed arrangement in which the internal diameter is smallerthan the internal diameter when in the normal, expanded arrangement. Inthe compressed arrangement, such a stent frame support structure withattached valve leaflets can be mounted onto a delivery device. The stentframe support structures are configured so that they can be changed totheir normal, expanded arrangement when desired, such as by the relativemovement of one or more outer sheaths relative to a length of the stentframe.

The wires of these stent frame support structures in embodiments of thepresent disclosure can be formed from a shape memory material such as anickel titanium alloy (e.g., Nitinol™). With this material, the supportstructure is self-expandable from the compressed arrangement to thenormal, expanded arrangement, such as by the application of heat,energy, and the like, or by the removal of external forces (e.g.,compressive forces). This stent frame support structure can also becompressed and re-expanded multiple times without damaging the structureof the stent frame. In addition, the stent frame support structure ofsuch an embodiment may be laser-cut from a single piece of material ormay be assembled from a number of different components. For these typesof stent frame structures, one example of a delivery device that can beused includes a catheter with a retractable sheath that covers the stentframe until it is to be deployed, at which point the sheath can beretracted to allow the stent frame to self-expand. Further details ofsuch embodiments are discussed below.

With the above understanding in mind, one non-limiting example of thestented prosthetic heart valve 22 useful with systems, devices, andmethods of the present disclosure is illustrated in FIG. 4A. As a pointof reference, the prosthetic heart valve 22 is shown in a normal orexpanded arrangement in the view of FIG. 4A; FIG. 4B illustrates theprosthetic heart valve 22 in a compressed arrangement (e.g., whencompressively retained within an outer catheter or sheath). Theprosthetic heart valve 22 includes a stent or stent frame 32 and a valvestructure 34. The stent frame 32 can assume any of the forms describedabove, and is generally constructed so as to be self-expandable from thecompressed arrangement (FIG. 4B) to the normal, expanded arrangement(FIG. 4A). In other embodiments, the stent frame 32 is expandable to theexpanded arrangement by a separate device (e.g., a balloon internallylocated within the stent frame 32). The valve structure 34 is assembledto the stent frame 32 and provides two or more (typically three)leaflets 36. The valve structure 34 can assume any of the formsdescribed above, and can be assembled to the stent frame 32 in variousmanners, such as by sewing the valve structure 34 to one or more of thewire segments defined by the stent frame 32.

With the but one acceptable construction of FIGS. 4A and 4B, theprosthetic heart valve 22 is configured for replacing or repairing anaortic valve. Alternatively, other shapes are also envisioned, adaptedto the specific anatomy of the valve to be repaired (e.g., stentedprosthetic heart valves in accordance with the present disclosure can beshaped and/or sized for replacing a native mitral, pulmonic, ortricuspid valve). With the one construction of FIGS. 4A and 4B, thevalve structure 34 extends less than the entire length of the stentframe 32, but in other embodiments can extend along an entirety, or anear entirety, of a length of the stent frame 32. A wide variety ofother constructions are also acceptable and within the scope of thepresent disclosure. For example, the stent frame 32 can have a morecylindrical shape in the normal, expanded arrangement.

With embodiments incorporating the self-expanding stent frame 32, theprosthesis 22 (and in particular the stent frame 32) is conventionallyconfigured to generate a high radially expansive force (alternativelyreferred to as a chronic outward force) when forced to the compressedarrangement of FIG. 4B, and exhibit high resistance to radialcompression (alternatively referred to as a radial resistive force orforce required to compress the stent frame 32) once in the expandedarrangement of FIG. 4A. As described below, these chronic outward forcesradial resistive forces render recapturing of the prosthesis 22 in apartially expanded arrangement exceedingly difficult. As a point ofreference, the chronic outward force/radial resistive forcecharacteristics of the prosthesis 22 can be determined by testing. Inparticular using an iris-type radial expansion force gauge, such as anMSI RX600 or RX650 available from Machine Solutions, Inc., of Flagstaff,Ariz. The stent frame 32 is loaded in a natural, relaxed, or expandedarrangement, and the force gauge operated to compress the stent frame 32down to the minimum contracted arrangement. During compression, theforce required the compress the stent frame 32 is monitored and loggedas a function of frame diameter to provide radial resistive force data.After compression to the minimum diameter representing the minimumdiameter when loaded to the delivery device 20 (FIG. 3), the stent frame32 is allowed to expand to the starting, unconstrained diameter. Inaccordance with the compression step described above, the expansionforce is monitored by the force gauge and logged as a function of stentframe diameter to provided chronic outward force data. Using thesemethodologies, in some embodiments, the stent frame 32 has a maximumradial resistive force of at least 25 lbf. For example, the stent frame32 of 26 mm and 29 mm CoreValve™ percutaneous aortic valves were testedin accordance with the above protocols at a temperature of approximately37° C. and constant strain rate of 0.5 mm/sec and found, when compressedto a diameter of 5.5 mm, to have a maximum or peak radial resistiveforce in excess of 25 lbf. In fact, the 26 mm and 29 mm CoreValvepercutaneous aortic valve stent frames exhibited radial resistive forcesapproaching and even exceeding 30 lbf at the 5.5 mm crimped diameter.Even with these elevated opening or radial resistive forces, it hassurprisingly been found that by incorporating the delivery capsule 28(FIG. 3) as described below, recapturing of the prosthesis 22 isconsistently achieved, even in the presence of a tortuous implantationsite (such as when curved along the aortic arch).

Returning to FIG. 3, the delivery capsule 28 is a beneficial feature ofthe device 20, and thus is initially described in detail below. Theremaining components of the delivery device 20 (e.g., the inner shaftassembly 24, the sheath assembly 26, and the handle 30) can assume awide variety of forms now known or in the future developed. In generalterms, however, the delivery capsule 28 is mounted to a sheath or shaft40 of the sheath assembly 26.

The delivery capsule 28 is generally formed as a tubular sleeve andincludes a cut tube (e.g., a laser cut tube) embedded or encapsulatedwithin a polymer. FIGS. 5A and 5B illustrate one embodiment of a lasercut tube 80 useful with the delivery capsule 28 of FIG. 3. FIG. 5C is atwo-dimensional or “unwrapped” representation of the tube 80,illustrating the cut pattern in greater detail. Various expansion andarticulation features imparted into the laser cut tube 80 are describedbelow, with a shape memory characteristic of the tube 80 facilitatingrepeatable transitioning of the delivery capsule 28 between a normal orcontracted state of FIG. 5A to a flared or expanded state of FIG. 5B. Inthis regard, various shape memory materials can be used for the tube 80,such as a steel, polymers, etc. In some embodiments, the tube 80 is aNitinol material, and in particular a Nitinol super elastic material.For example, in some non-limiting embodiments, the tube 80 is a Nitinolsuper elastic material composition per ASTM 2063-05 and ASTM F 2063-00,composed of 55.94% Nitinol, 227 ppm oxygen, 9 ppm hydrogen, 280 ppmcarbon, and the balance of titanium. Other materials are alsoacceptable. Similarly, the encapsulating polymer can assume variety offorms exhibiting biocompatibility, as well as bonding compatibility witha material of the sheath 40 (FIG. 3). For example, the encapsulatingpolymer can be Pebax. Other materials useful as the encapsulatingpolymer are described below.

The delivery capsule 28, and in particular the tube 80, defines or isdefined by a proximal zone 90, a distal zone 92, and one or moreintermediate zones 94. The proximal zone 90 is configured for mountingto a distal end of the sheath 40 (FIG. 3), and in some constructionsincludes a plurality of circumferentially-spaced fingers 100, eachterminating a proximal end 102. In some constructions, the proximal end102 of each of the fingers 100 can have an enlarged width as shown.Regardless, the spaced fingers 100 are readily interposed within(alternatively over) the distal end of the sheath 40 so as to facilitateattachment thereto (e.g., adhesive bond, heated fusing, etc.).

The distal zone 92 is configured to provide a circumferentially flaringfeature, transitioning from the normal or non-flared state of FIG. 5A tothe flared state of FIG. 5B when subjected to an expansion force, andself-transitioning back toward the normal state when the expansion forceis removed. In this regard, the distal zone 92 is specificallyconstructed so as to reduce the force required to recapture apartially-deployed transcatheter valve prosthesis, while increasing theaxial strength and buckling resistance of the delivery capsule 28 (FIG.3). For example, in some embodiments, the tube 80 at the distal zone 92includes a lattice or scaffolding segment 110 and a base or collarsegment 112. The lattice segment 110 includes a plurality of generallylongitudinally extending splines or struts 114 extending distally fromthe base 112 to a distal end 116. In the one embodiment of FIGS. 5A-5C,the splines 114 are oriented to extend parallel with the central axis ofthe tube 80. For example, with respect to first and second splines 114a, 114 b identified in FIGS. 5A and 5C, extension of the spines 114 a,114 b from the base 112 are parallel with one another and with thecentral axis. Alternatively, in the normal state of FIG. 5A, the splines114 can deviate from a true longitudinal orientation (relative to acentral axis of the tube 80). Regardless, the splines 114 are eachdeflectable or pivotable relative to the base 112, pivoting ordeflecting a pivot point (identified at 118 in FIGS. 5A and 5C) or pointof departure from the base 112. With this construction, then,transitioning between the normal and flared states includes each of thesplines 114 pivoting relative to the base 112 at the corresponding pivotpoint 118. As further clarified by a comparison of FIGS. 5A and 5B, aninner diameter defined at the distal end 116 of the distal zone 92 isincreased in the flared state (FIG. 5B) as compared to the normal state(FIG. 5A), with the delivery capsule 28 again being constructed tonaturally assume (via shape memory) the normal or relaxed state.

Circumferential stability of the lattice segment 110 is enhanced byinterconnecting adjacent pairs of the splines 114 at correspondingdistal ends 119. For example, the distal ends 119 of the splines 114 a,114 b are connected at a distal bond point 120 a; similarly, the distalends 119 of the splines 114 c, 114 d are interconnected at a bond point120 b. However, the distal end 119 of the second spline 114 b is notdirectly connected or bonded the distal end 119 of the third spline 114c. Additionally, intermediate bond points 121 are also included betweenvarious adjacent splines 114.

To promote a desired resistance to circumferential expansion (i.e.,resistance to transitioning from the collapsed state to the flaredstate) and/or inward radial biasing force (i.e., force generated by theshape memory attribute in self-transitioning from the flared state tothe contracted or collapsed state), the distal zone 92 can furtherinclude an undulating or sinusoidal-like strut 122 that interconnectsthe distal bond points 120, and thus the distal end 119 of adjacent onesof the splines 114. The undulating strut 122 can be continuous as shown,or can be comprised of discrete strut segments. Regardless, theundulating shape of the strut 122 generates a series of overlappingloops 124 as best shown in FIG. 6. The loops 124 each form a crown 126at the distal end 116 of the tube 80. The crowns 126 are rounded foratraumatic interface with the prosthetic valve 22 (FIG. 4A). To minimizethe propensity for tearing, delamination, and/or catching on the stentedheart valve prosthesis 22 (FIG. 4A), a variety of other crown shapes orconfigurations can be employed. Further, the overlapping nature of theloops 124 renders the strut 122 less resistant to radial expansion (ascompared to a resistance of the lattice segment 110). Returning to FIGS.5A-5C, with embodiments incorporating the continuous strut 122, thedistal zone 92 has been found to maintain its expansion properties whileincreasing its resistance to delamination and tear.

The base or collar segment 112 can be circumferentially more rigid ascompared to the lattice segment 110, and provides a more robustresistance to a radially outward force. Thus, the base 112 can includecircumferentially-spaced cut-outs 128 as shown, although otherconfigurations are also acceptable.

As indicated above, the tube 80, and thus the delivery capsule 28 (FIG.3), can include one or more of the intermediate zones 94. With the oneembodiment of FIGS. 5A-5C, for example, the delivery capsule 28 includesor defines an intermediate flex zone 94 a that is longitudinallydisposed between the proximal and distal zones 90, 92. In general terms,the flex zone 94 a incorporates features that impart circumferential orradial rigidity, yet permit or promote transverse articulation, designedto give the delivery capsule 28 adequate axial and radial strength toprevent buckling or kinking. For example, in some embodiments, the tube80 includes, along the intermediate flex zone 94 a, a partial coil orhelix-like cut pattern 130 that establishes a plurality of generallycircumferentially extending coil segments 132. Longitudinally adjacentones of the coil segments 132 are separated by a cut 134. The cuts 134are circumferentially discontinuous, extending less than 180°. As such,the first and second cuts 134 a, 134 b identified in FIG. 5C arehelically aligned, but are separated from one another. Thus, the cutpattern 130 establishes one or more longitudinal spines 136. With theconstruction of FIGS. 5A-5C, two of the spines 136 are formedcircumferentially opposite one another (it being understood that onlyone of the spines 136 is visible in FIGS. 5A and 5B, and that in theflat or unwound representation of FIG. 5C, only one of the spines 136 isreadily identifiable).

The discontinuous cuts 134 and the spines 136 generally connect ormaintain adjacent ones of the coil segments 132 relative to one another,yet permit transverse articulation. The coil segments 132 can thusarticulate from the relatively straight arrangement of FIG. 5A to thearticulated or curved orientation reflected in FIG. 5B. Otherconstructions that promote desired transverse articulation are alsoenvisioned. Bond sites can be added, for example, to decrease an overallthickness of the tube 80 and increase bond strength (to theencapsulating polymer). Increasing the bondable area decreases theamount of movement of the tube 80 within the encapsulating polymer,thereby reducing the potential for delamination. While being flexiblefor requisite bending or articulation (due to a material strength,thickness, and circumferential width), the spines 136 (in combinationwith the coil segments 132) provide an enhanced hoop strength attributeto the zone 94 a, to constrain the prosthesis 22 (FIG. 4A) in thecollapsed arrangement as well as longitudinal stability for distallyadvancing the delivery capsule 28 over a partially deployed (andradially expanded) prosthesis as described below. Further, the deliverysheath 40 (FIG. 3) can incorporate complimentary spine-like componentsas described below. With these and other embodiments, the tube 80 can beconfigured to readily identify a location of the spines 136 to a user.For example, the finger(s) 100 of the proximal zone 90 otherwise alignedwith one of the spines 136 can have a unique shape or identifier 138 asshown in FIG. 5C.

The delivery capsule 28 can include additional intermediate zones, suchas the second intermediate zone 94 b identified in FIGS. 5A-5C. Ingeneral terms, the second intermediate zone 94 b serves to provide amore robust columnar strength as well as more rigid resistance to radialexpansion, and is configured to constrain the stented heart valveprosthesis 22 (FIG. 4A) in or near the collapsed arrangement. Thus, insome constructions, the second intermediate zone 94 b consists or formsa plurality of longitudinal and circumferential segments 140, 142 thatare interconnected to one another and combine to resist radialexpansion.

Other constructions of the flex zone 94 are also acceptable, and in someembodiments, the second intermediate zone 94 b can be omitted. Forexample, while the coil segments 132 are shown as having a uniformpitch, in other embodiments, a variable pitch construction is employed(e.g., a distally increasing pitch). FIG. 5D illustrates a portion of analternative laser cut tube 80′, and in particular a flexibleintermediate zone 94′ thereof. A cut pattern 130′ has a dovetail-likeshape, defining segments 132′ that can flex or articulate relative toone another when the intermediate zone 94′ is subjected to a transversebending force. The intermediate zone 94′ exhibits enhanced columnarstrength and is readily flexed.

Returning to FIG. 5A, as indicated above, the core of the deliverycapsule 28 can be the laser cut tube 80. In some constructions, the tube80 is initially provided as a Nitinol hypo-tube into which the latticeor scaffolding-like structure(s) are formed. For example, onenon-limiting, simplified example of the delivery capsule 28, includingthe laser cut tube 80 (shown without the cut patterns for ease ofillustration) and encapsulating polymer 82, is shown in FIG. 7. In theseand other embodiments, the polymer encasement 82 extends distally andproximally beyond the core tube 80. Alternatively, the polymerencasement 82 can terminate at the opposing ends of the tube 80.

Nitinol is employed for the tube 80 due to its ability to recover afterexperiencing high forces and deformation. Nitinol's mechanicalproperties allow the cut tube 80 structure to expand and return to itsoriginal shape, providing the flared or funnel shape for reduction inretraction forces. Following cutting, the tube 80 can be de-burred byhand filing using a round filing mandrel. Additional processing, such asmicro-blasting, can also be performed. Subsequently, the tube 80 can berinsed in IPA and placed into a BS acid etch solution (e.g., for oneminute). The acid can be heated to 40° C. while ultrasonically vibrated.Additional processing (e.g., electro-polishing to remove sharp edges,micro-cracks, reduce wall thickness, etc.), can also be performed.

The polymer encasement 82 can be applied to the laser cut tube 80 in avariety of fashions, for example, dip coating, heat fusing, etc. Thematerials selected for the polymer encasement 82 can vary. For example,the encasement 82 can be formed by inner and outer liner materialsapplied to the laser cut tube 80, with the liner material beingidentical or at least similar in their chemical makeup. The selectedliner material(s) exhibit, in some constructions, a balance between highstrength, low elastic hysteresis, and lubricity. For example, the linermaterial(s) can be Elasthane, Pellethane™, Pebax, Grilamide™, etc. Insome embodiments, the polymer encasement 82 is a polyblend formulated asa modified thermoplastic polyether urethane. Elasthane™ 80A TPU(available from DSM PTG of Berkeley, Calif. (formerly The PolymerTechnology Group)) can be used as the principal component of thepolyblend because of its moderate strength, low elastic hysteresis, andhistory of use in biomedical applications. A siloxane polymer inpolyurethane carrier resin can be selected as the other component ofthis polyblend, to impart lubricity without causing migration orblooming. In some constructions, these two components are melt-blendedin a single-screw extruder in 90:10 and 80:20 weight ratios. Theresultant polyblends exhibit the same low elastic hysteresis behavior asElasthane™ 80A TPU when their tubing forms were radially expanded toabout 300% for 5 consecutive times. The 90:10 and 80:20 polyblendsshowed about 190% and 205% higher yield strength than Elasthane™ 80ATPU. The 90:10 and 80:20 polyblends were also found to be about 12% and53% more lubricious than Elasthane™ 80A TPU. Considering these results,the 80:20 polyblend of Elasthane™ 80A TPU and siloxane masterbatchoffers an attractive option to modify a commercially available medicalgrade polymer, achieving the desired combination of conflictingproperties for the polymer encasement 82. It has surprisingly been foundthrough testing that the polymer blend described above has a much highertear load than the base material. By blending thermoelastomers with asiloxane masterbatch or silicone-containing material, a new materialwith good elasticity, better lubricity, and higher tear load is achievedand is highly useful for a stented prosthetic heart valve deliverycapsule. The base polymers can be SBS, SIBS, thermoelastic polyurethane,polyamide, etc. The ratio of the siloxane masterbatch can be in therange of 5-50%.

Returning to FIGS. 5A-5C, by employing the flarable distal zone 92, thedelivery capsule 28 redistributes the radial force energy curve,reducing the overall forces for retraction while performing the sameamount of work. With the ability to flare, the peak forces necessary tocompress the stented heart valve prosthesis 22 (FIG. 4A) is reduced. Thefunnel or flared shape created by the expanded distal zone 92 alsoreduces the potential for interference with pillowing tissue and/orskirt material. FIG. 8 is a graph illustrating the force redistributioneffectuated by the flarable distal zone 92 as compared to a linear orstraight configuration.

Returning to FIG. 3, remaining components of the delivery device 20 canassume a variety of forms appropriate for percutaneously delivering anddeploying a stented self-expanding prosthetic heart valve. Oneembodiment of the delivery device 20 is shown in greater detail in FIG.9 and includes the inner shaft assembly 24, the sheath assembly 26, thedelivery capsule 28, the handle 30, and an optional stability tube 150.The inner shaft assembly 24 can have various constructions appropriatefor supporting a stented prosthetic heart valve within the deliverycapsule 28. In some embodiments, the inner shaft assembly 24 can includea retention member 200, an intermediate tube 202, and a proximal tube204. In general terms, the retention member 200 can be akin to aplunger, and incorporates features for retaining the stented prostheticheart valve within the delivery capsule 28 as described below. The tube202 connects the retention member 200 to the proximal tube 204, with theproximal tube 204, in turn, coupling the inner shaft assembly 24 withthe handle 30. The components 200-204 can combine to define a continuouslumen 206 (referenced generally) sized to slidably receive an auxiliarycomponent such as a guide wire (not shown).

The retention member 200 can include a tip 210, a support tube 212, anda spindle 214. The tip 210 forms or defines a nose cone having adistally tapering outer surface adapted to promote atraumatic contactwith bodily tissue. The tip 210 can be fixed or slidable relative to thesupport tube 212. The support tube 212 extends proximally from the tip210 and is configured to internally support a compressed, stentedprosthetic heart valve generally disposed thereover, and has a lengthand outer diameter corresponding with dimensional attributes of theselected prosthetic heart valve. The spindle 214 is attached to thesupport tube 212 opposite the tip 210 (e.g., an adhesive bond), andprovides a coupling structure 220 (referenced generally) configured toselectively capture a corresponding feature of the prosthetic heartvalve. The coupling structure 220 can assume various forms, and isgenerally located along an intermediate portion of the inner shaftassembly 24. In some constructions, the coupling structure 220 forms oneor more slots sized to slidably receive a corresponding component(s) ofthe prosthetic heart valve (e.g., a bar or leg segment of the stentframe). Further, the inner shaft assembly 24 can incorporate additionalstructures and/or mechanisms that assist in temporarily retaining thestented valve (e.g., a tubular sleeve biased over the spindle 214), suchas described in U.S. application Ser. No. 12/870,567 entitled“Transcatheter Valve Delivery Systems and Methods” filed Aug. 27, 2010and the entire teachings of which are incorporated herein by reference.Other releasable coupling arrangements are also acceptable, such as thespindle 214 including one or more fingers sized to be received withincorresponding apertures formed by the prosthetic heart valve stent frame(e.g., the prosthetic heart valve stent frame can form wire loops at aproximal end thereof that are received over respective ones of thefingers when compressed within the capsule 28).

The intermediate tube 202 is formed of a flexible polymer material(e.g., PEEK), and is sized to be slidably received within the deliverysheath assembly 26. The proximal tube 204 can include, in someembodiments, a leading portion 222 and a trailing portion 224. Theleading portion 222 serves as a transition between the intermediate andproximal tubes 202, 204 and thus in some embodiments is a flexiblepolymer tubing (e.g., PEEK) having a diameter slightly less than that ofthe intermediate tube 202. The trailing portion 224 has a more rigidconstruction, configured for robust assembly with the handle 30 such asa metal hypotube. Other constructions are also envisioned. For example,in other embodiments, the intermediate and proximal tubes 202, 204 areintegrally formed as a single, homogenous tube or solid shaft.

The delivery sheath assembly 26 includes the sheath 40 that is connectedto the delivery capsule 28, and defines proximal and distal ends 232,234. With embodiments in which the delivery capsule 28 is considered tobe “part” of the delivery sheath assembly 26, then, the delivery capsule28 defines the distal end 234. The delivery sheath or shaft 40 in someembodiments has a less stiffened construction (as compared to astiffness of the delivery capsule 28). For example, the delivery sheath40 can be a polymer tube embedded with a metal braiding. The deliverysheath 40 is constructed to be sufficiently flexible for passage througha patient's vasculature, yet exhibit sufficient longitudinal rigidity toeffectuate desired axial movement of the delivery capsule 28. In otherwords, proximal retraction of the delivery sheath 40 is directlytransferred to the capsule 28 and causes a corresponding proximalretraction of the capsule 28. In other embodiments, the delivery sheath40 is further configured to transmit a rotational force or movement ontothe capsule 28.

In other embodiments, the delivery sheath 40 can be longitudinallyreinforced with one or more wires. FIG. 10 is a simplified illustrationof the optional delivery sheath 40 construction, and includes, inner andouter tubular layers 236 a, 236 b encapsulating a braid 237 andcircumferentially opposite wires 238 a, 238 b. The tubular layers 236 a,236 b can be formed of identical or differing polymer materials (e.g.,the inner tubular layers 236 a can be PTFE, nylon, PE TPE, etc., and theouter tubular layer 236 b can be EVA, PVC, etc., or other lubriciouspolymers). The braid 237 can be a conventional metal braid (e.g.,stainless steel braiding) and in other embodiments can be omitted. Thewires 238 a, 238 b can be made of a structurally robust material, suchas stainless steel, and have the flattened or rectangular shape in someembodiments as illustrated. While other shapes are also acceptable, theflattened construction provides more mass and thus an enhanced abilityto “steer” the delivery capsule 28 (FIG. 3) around a bend as describedbelow.

The wires 238 a, 238 b effectively serve as longitudinal spines. As apoint of reference, a major challenge for a delivery system thatdelivers an aortic valve through percutaneous implantation is theability to be flexible enough to track through the aortic arch and thenhave the ability to stretch and compress minimally so that the deliverydevice can accurately deploy the prosthesis. Within the outer and/orinner shaft(s) 236 a, 236 b, the longitudinal wires, tapered wires orcables 240 are located 180 degrees apart from each other. Alternatively,two or more of the wires 238 can be included on each side. The resultantsheath 40 can bend back and forth in one direction, but not in theopposite. This characteristic, in turn, forces the delivery capsule 28(FIG. 9) to rotate so that the wires 238 make the delivery capsule 28take the path with the least resistance. By having the wires or cables238 within the shaft(s) 236 a, 236 b, they are much stronger in tensionand much more resistant to compression. Additionally, the distal end ofthe wires or cables 238 can be tapered to allow for added flexibility.The distal wires 238 can also be pre-shaped to “point” the deliverycapsule 28 in the correct direction for tracking over the arch,effectively causing the delivery capsule 28 to rotate to a desiredorientation as the delivery capsule 28 and sheath 40 successivelytraverse the aortic arch. In some embodiments, if the “preshaping”imparted by the wires 238 limits an ability of the delivery sheath 40 toproperly track through the expected anatomy (e.g., the descendingaorta), the optional stability tube 150 (FIG. 9) can be provided. Thestability tube 150 is a polymer-based tube or catheter that is slidablydisposed over the sheath 40. Where provided, the stability tube 150renders the delivery sheath 40 straightened; once the delivery sheath 40has been advanced to the anatomical location where bending is desired,the stability tube 150 is retracted, permitting the sheath 40 to morereadily bend. Alternatively, the wires or spines 238 can be omitted.

Returning to FIG. 9, the handle 30 generally includes a housing 240 andone or more actuator mechanisms 242 (referenced generally). The housing240 maintains the actuator mechanism(s) 242, with the handle 30configured to facilitate sliding movement of the delivery sheathassembly 26 relative to the optional stability tube 150 and the innershaft assembly 24, as well as the stability tube 150 relative to theinner shaft assembly 24 and the delivery sheath assembly 26. The housing240 can have any shape or size appropriate for convenient handling by auser. In one simplified construction, a first, deployment actuatormechanism 242 a includes a user interface or actuator 244 slidablyretained by the housing 240 and coupled to a delivery sheath connectorbody 246. The proximal end 232 of the delivery sheath assembly 26 isconnected to the delivery sheath connector body 246. The inner shaftassembly 24, and in particular the proximal tube 204, is slidablyreceived within a passage 248 (referenced generally) of the deliverysheath connector body 246, and is rigidly coupled to the housing 240. Asecond, stability tube actuator mechanism 242 b (referenced generally)similarly includes a user interface or actuator 250 moveably maintainedby the housing 240 and coupled to the stability tube 150 via one or morebodies (not shown) facilitating movement of the stability tube 150 withoperation of the stability actuator 250. With this but one acceptableconstruction, the deployment actuator 244 can be operated to effectuateaxial movement of the delivery sheath assembly 26 relative to thestability tube 150 and the inner shaft assembly 24. Similarly, thestability actuator 250 can be manipulated to axially slide the stabilitytube 150 relative to the inner shaft assembly 24 and the delivery sheathassembly 26. In other embodiments, the handle 30 can have a moresimplified form, such as when the stability tube 150 is omitted.

The delivery system 18 is operable to deliver or implant the stentedheart valve prosthesis 22 (FIG. 4A) as described below. FIGS. 11A and11B illustrate the delivery device 20 loaded with the stented heartvalve prosthesis 22 prior to deployment. In particular, and as bestshown in FIG. 11A, the stented heart valve prosthesis 22 is connected orcrimped to the inner shaft assembly 24 via the spindle 214, and isradially constrained to the compressed arrangement within the deliverycapsule 28. In some constructions, a majority of the prosthesis 22 iswithin the intermediate zone 94 of the delivery capsule 28. As a pointof reference, the intermediate zone 94 has an increased resistance toradial expansion (as compared to a resistance along the distal zone 92),such that when the prosthesis 22 is located within the intermediate zone94, the prosthesis 22 is held in the compressed arrangement. Theoptional stability tube 150 is positioned proximal the distal capsule28.

The loaded delivery device 20 can then be used to percutaneously deliverthe prosthetic heart valve 22 to an implantation site, such as adefective heart valve. For example, the delivery device 20 ismanipulated to advance the compressed prosthetic heart valve 22 towardthe implantation target site in a retrograde manner through a cut-downto the femoral artery, into the patient's descending aorta. The deliverydevice 20 is then advanced, under fluoroscopic guidance, over the aorticarch, through the ascending aorta, and approximately midway across thedefective aortic valve (for an aortic valve replacement procedure). Oncepositioning of the delivery device 20 is estimated, the delivery capsule28 (and the sheath 40) are partially retracted (proximally) relative tothe prosthesis 22 as generally reflected in FIGS. 12A and 12B. As shown,a distal region 300 of the prosthesis 22 is thus exteriorly “exposed”relative to the delivery capsule 28, and is allowed to self-expand. FIG.12C illustrates the system 18 percutaneously directed to a native valveand the delivery device 20 in a partially retracted state; as shown, theprosthetic heart valve 22 is partially deployed or expanded, yet remainssecured to the delivery device 20.

In FIGS. 13A and 13B, proximal retraction of the delivery capsule28/sheath 40 continues, with an increased length of the prosthesisdistal region 300 being exposed and thus self-expanded toward theexpanded arrangement. In the state of FIGS. 13A and 13B, however, atleast a proximal segment 302 of the prosthesis 22 remains within theconfines of the delivery capsule 28, and thus coupled to the deliverydevice 20. In this partially deployed state, a substantial portion(e.g., 90%) of the stented prosthetic heart valve 22 has self-expandedtoward the expanded condition.

In the stage of partial deployment of FIGS. 13A and 13B (or any othersequentially prior stage of deployment), the clinician can performdesired evaluations of the prosthesis 22 relative to the implantationsite. Notably, a substantial majority of the prosthetic 22 is expanded,including, for example, the inflow region and at least a portion of theoutflow region. In the event the clinician believes, based upon theabove evaluation, that the prosthesis 22 should be repositioned relativeto the implantation site, the prosthesis 22 must first be contracted or“resheathed”. As shown in FIGS. 14A and 14B, the delivery capsule28/sheath 40 is advanced distally relative to the inner shaft assembly24, and thus relative to the stented heart valve prosthesis 22. Thedistal zone 92 of the capsule 28 interfaces with an exterior of theprosthesis 22, and, in response, flares and expands. This action reducesthe force imparted upon the stented heart valve prosthesis 22, thuslessening the likelihood of tearing or other damaging interaction.However, column strength for resheathing is maintained. In FIGS. 15A and15B, distal movement of the delivery capsule 28/sheath 40 continuesuntil the stented heart valve prosthesis 22 is fully resheathed withinthe delivery capsule 28. The delivery capsule 28 may slightly expandradially; however, the prosthesis 22 is forced back to approximately theinitial, collapsed arrangement (of FIGS. 12A and 12B). In accordancewith embodiments of the present disclosure, recapture of the prosthesis22 is accomplished using the same components of the delivery device 20otherwise employed during prosthesis deployment. In other words,systems, devices, and methods of the present disclosure do not requireany additional moving components to effectuate recapture in someembodiments. Instead, the same actuator operated during deployment isoperated, in reverse fashion, to accomplish recapture.

Once resheathed or recaptured, the system 18 can be repositionedrelative to the implantation site, and the process repeated until theclinician is comfortable with the achieved positioning. In this regard,because the distal zone 92 has self-transitioned back toward the normalor unflared state, the delivery capsule 28 has returned to a relativelylow profile and thus is readily moved or “re-crossed” relative to thenative valve. As a point of reference, were the distal zone 92 to remainin the flared state, the corresponding elevated diameter may renderre-crossing of the native valve difficult. Once properly positioned, thestented prosthetic heart valve 22 is fully released from the deliverydevice 20 by retracting the delivery capsule proximally beyond theprosthesis 22. FIG. 16 reflects that the released prosthetic heart valve22 is now implanted to the native valve. Alternatively, the resheathedstented heart valve prosthesis 22 can be removed from the patient.

As a point of reference, there needs to be a balance between the lengthof the flared distal zone 92 (FIG. 5B) and the reliability of thedelivery capsule 28 because resheathing or recapture would usually bedone over the arch of the aorta, and a flare that is too long has a highchance of buckling when bent during recapture. To reduce the likelihoodof buckling, the articulating or flexing section or zone 94 a (FIG. 5B)is optionally provided just behind the distal flarable zone 92. By wayof further explanation, to recapture the prosthetic heart valve 22, theprosthesis 22 must go from an expanded or natural arrangement to acollapsed arrangement over a given distance. The present disclosureenvisions that in some embodiments, the partially deployed state entailstwo-thirds of the length of the prosthesis 22 being deployed. In orderto reduce the force required of the delivery capsule 28 to effectuaterecapture, the distance of interface between the prosthesis 22 and thedelivery capsule 28 can be increased; this is accomplished by theflarable distal zone 92. It has been surprisingly found through testingthat the delivery capsule 28 as described above will successfullyrecapture an expanded stented prosthetic heart valve having a maximumradial resistive force of at least 25 lbf, and recover to its original,normal size when the outward radial force of the prosthesis 22 isremoved (e.g., when the flarable distal zone 92 is advanced distal theprosthesis 22) thereby facilitating ready “re-crossing” of the nativevalve. These same valves were found to not experience infolding due tothe distribution of work to collapse the stent frame cells over agreater length and minimization of the radial crimping force. Also, withthe high radial resistive force prosthetic valves described above, thedelivery device 20 will experience forces on the order of 15-40 lbs.when recapturing. The delivery capsules of the present disclosure weresurprisingly found to not buckle under these conditions due, at least inpart, to their high columnar strength (e.g., the spines 136 (FIG. 5C)).

The delivery capsule 28 described above, and in particular the laser cuttube 80, is but one acceptable construction in accordance withprinciples of the present disclosure. For example, FIGS. 17A-17Cillustrate an alternative laser cut tube 350 useful with the deliverycapsule 28 (FIG. 3) described above. The tube 350 is formed of a shapememory material (e.g., NiTi), and is cut to define a proximal zone 352,a distal flarable zone 354 and one or more intermediate zones 356. Theproximal zone 352 is akin to the proximal zone 90 (FIG. 5A) describedabove, and can form fingers 358 that facilitate attachment to thedelivery sheath 40 (FIG. 3). The distal zone 354 defines a latticeregion 360 that will flare from the normal state of FIG. 17A to theflared state of FIG. 17B in response to a radially expansive force (suchas when the distal zone 354 is advanced over an expanded portion of astented prosthetic heart valve). Upon removal of the radially expansiveforce, the distal zone 354 self-transitions back toward the normalstate. Finally, the intermediate zones 356 includes an articulatingregion 362 defined by circumferential cuts 364, and a support region 366having a plurality of spaced cut-outs 368. The articulating region 362is articulately or deflectable as shown in FIG. 17C, while the supportregion 366 provides columnar strength and more overt resistance toradial expansion. When employed as part of the delivery capsule 28(e.g., encapsulated within a polymer and attached to the delivery sheath40), the tube 350 operates in a manner akin to previous descriptions.

FIGS. 18A-18C illustrate another laser cut tube 400 useful with thedelivery capsule 28 (FIG. 3) described above. As with previousembodiments, the tube 400 is formed of a shape memory material (e.g.,Nitinol) and defines a proximal zone 410, a distal zone 412, and one ormore intermediate zones 414. The proximal zone 410 can be akin to theproximal zone 90 (FIG. 5A) described above, and effectuates attachmentto the sheath 40 (FIG. 9). The distal zone 412 is also akin to thedistal zone 92 (FIG. 5A) described above, and is configured tofacilitate flaring to a distal end 416 when subjected to an internalexpansion force. The first intermediate zone 414 a provides forarticulation or flexing as described above.

The second intermediate zone 414 b is formed between the distal zone 412and the first intermediate zone 414 a, and is expandable so as to lessenthe forces required for recapturing the stented heart valve prosthesis22 (FIG. 4A). The second intermediate or expandable zone 414 b can beformed as a continuation of the distal zone 412, comprised of alattice-like or scaffolding-like arrangement. For example, a pluralityof spines or struts 418 are provided, interconnected at bond points 420.In the normal or collapsed state of FIG. 18A, the distal zone 412 andthe expandable zone 414 b are collapsed, approximating a uniformdiameter. In conjunction with the implantation methodologies describedabove, recapturing of a stented heart valve prosthesis can include thedistal zone 412 flaring to an increased diameter at the distal end 416,effectively pivoting relative to the second intermediate zone 414 a asshown in FIG. 18A. With further distal movement of the delivery capsule28, the expandable zone 414 b will expand, with the distal zone 412collapsing about a distal end of the prosthesis as shown in FIG. 18C.Thus, the delivery capsule 28 is allowed to flare circumferentially atthe distal end 416 and expand at the expandable zone 414 b, therebyreducing the force required to recapture the stented heart valveprosthesis while increasing the axial strength and buckling resistance.

By way of further explanation, the tube 400 reflects an effort to reducethe force required for partially deployed transcatheter heart valverecapturing in a manner differing slightly from the tube 80 (FIG. 5A)described above. As discussed previously, it has been determined that insome instances, increasing a length of the flarable zone (e.g., thedistal zone 92 (FIG. 5A)) is not viable because it may become unstableover tight bends. If distance of interface cannot be reduced, then theonly way to further reduce the requisite recapture force is to reducework required. Since work is a measure of energy expended in applying aforce to move an object, the expandable zone 414 b simply serves to notmove the object (i.e., the stented prosthetic heart valve) as far. Moreparticularly, with the tube 400 configuration, the prosthesis isintentionally not forced completely back to the fully collapsed state.

While the tubes 80, 350, 400 have been described as being integral orhomogenous bodies, in other embodiments, portions of the tube can beseparately formed. With this in mind, FIGS. 19A and 19B illustrateanother embodiment tube 500 useful with the delivery capsule 28 (FIG.3). The tube 500 includes first and second tube sections 502, 504. Thetube sections 502, 504 are formed (e.g., laser cut tube) separate fromone another (as in FIG. 19A), and thus can have different properties(e.g., materials, wall thickness, diameters, etc.). The first tubesection 502 is laser cut to have a flarable attribute, and thus issimilar to any of the distal zones described above (e.g., the distalzone 92 of FIG. 5A). The second tube section 504 is laser cut to haveattriculatable and columnar strength attributes, and thus is similar toany of the intermediate zones described above (e.g., the intermediatezones 94 of FIG. 5A). In addition, the first and second tube sections502, 504 each form a complementary part 510, 512 of a locking mechanism514 (referenced generally). For example, the locking parts 510, 512 caninclude a dovetail cut pattern at the end of each tube section 502, 504,with the parts 510, 512 locking to one another upon final assembly as inFIG. 19B. With the embodiment of FIGS. 19A and 19B, differentlyconstructed tube sections 502, 504 having desired properties can beformed and easily assembled.

The heart valve replacement systems, delivery devices, and methods ofpresent disclosure provide a marked improvement over previous designs.The delivery capsule is attached to the outer delivery. This means thatthere is no secondary shaft to accomplish desired recapture, andtherefore does not add additional parts to the delivery device orcomplexity to the user. The delivery capsules are not flared in theinitial, loaded state. Instead, they are “flarable” meaning that theyonly flare at the distal end in response to a radial force and areelastic in their flaring so that once the transcatheter heart valve isrecaptured, the capsule returns to or toward its natural or unflaredshape, making re-crossing of the native valve easy. In some embodiments,the delivery capsule has an expandable region which allows less force tobe exerted to capture the prosthetic heart valve. With theseembodiments, the expandable region need not be expanded to start with.Instead, it expands in response to a radial force and is elastic inexpansion such that once the prosthetic heart valve is deployed, thedelivery capsule returns to its unexpanded shape. Further, bydistributing the work to collapse the stent frame cells over a greaterlength and minimizing the radial crimping force, the delivery capsulesof the present disclosure markedly reduce occurrence of infolding of thestent frame during recapture. Also, the delivery capsules truly reducethe force on the sheath and handle to effectuate recapture, allowing fora lower profile component and thus a smaller delivery device. Theflarable regions of the present disclosure have surprisingly been foundto reduce the retraction force and instability by expanding, providesufficient axial strength to not buckle while recapturing, recover to ortoward a normal or unflared state following recapture, and limit alength of the flare so that the prosthesis can be functional whenpartially deployed. The optional flex regions of the present disclosurehave surprisingly been found to provide enough columnar strength to notbuckle while recapturing, provide enough flexibility to track to thedeployment site without excessive force or harm to the patient, provideenough flexibility to position the stented prosthetic valve accuratelyand predictably, and provide sufficient radial strength and flexibilityto not kink while tracking through a tortuous anatomy.

The delivery devices of the present disclosure provide for placement ofa stent for replacement of an aortic valve, for example. Alternatively,the systems and devices of the present disclosure can be used forreplacement of other valves and/or in other portions of the body inwhich a stent is to be implanted. When delivering a valved stent toreplace an aortic valve, the delivery devices of the disclosure can beused with a retrograde delivery approach, for example, although it iscontemplated that an antegrade delivery approach can be used, withcertain modifications to the delivery device. With the systems describedherein, full or partial blood flow through the valve can advantageouslybe maintained during the period when the valved stent is being deployedinto the patient but is not yet released from its delivery device. Thisfeature can help to prevent complications that may occur when blood flowis stopped or blocked during prosthetic valve implantation with someother known delivery devices. In addition, it is possible for theclinician to thereby evaluate the opening and closing of leaflets,examine for any paravalvular leakage and evaluate coronary flow andproper positioning of the valve within the target anatomy before finalrelease of the valved stent.

The delivery devices shown and described herein can be modified fordelivery of balloon-expandable stents, within the scope of the presentdisclosure. That is delivering balloon-expandable stents to animplantation location can be performed percutaneously using modifiedversions of the delivery devices of the disclosure. In general terms,this includes providing a transcatheter assembly which may includerelease sheaths and/or additional sheaths and/or collars includingindentations and/or grooves, as described above. These devices canfurther include a delivery catheter, a balloon catheter, and/or a guidewire. A delivery catheter used in this type of device defines a lumenwithin which the guide wire is slidably disposed. Further, the ballooncatheter includes a balloon that is fluidly connected to an inflationsource. It is noted that if the stent being implanted is theself-expanding type of stent, the balloon would not be needed and asheath or other retraining means would be used for maintaining the stentin its compressed state until deployment of the stent, as describedherein. In any case, for a balloon-expandable stent, the transcatheterassembly is appropriately sized for a desired percutaneous approach tothe implantation location. For example, the transcatheter assembly canbe sized for delivery to the heart valve via an opening at a carotidartery, a jugular vein, a sub-clavian vein, femoral artery or vein, orthe like. Essentially, any percutaneous intercostals penetration can bemade to facilitate use of transcatheter assembly.

With the stent mounted to the balloon, the transcatheter assembly isdelivered through a percutaneous opening (not shown) in the patient viathe delivery catheter. The implantation location is located by insertingthe guide wire into the patient, which guide wire extends from a distalend of the delivery catheter, with the balloon catheter otherwiseretracted within the delivery catheter. The balloon catheter is thenadvanced distally from the delivery catheter along the guide wire, withthe balloon and stent positioned relative to the implantation location.In an alternative embodiment, the stent is delivered to an implantationlocation via a minimally invasive surgical incision (i.e.,non-percutaneously). In another alternative embodiment, the stent isdelivered via open heart/chest surgery. In one embodiment of the stentsof the disclosure, the stent includes a radiopaque, echogenic, or MRIvisible material to facilitate visual confirmation of proper placementof the stent. Alternatively, other known surgical visual aids can beincorporated into the stent. The techniques described relative toplacement of the stent within the heart can be used both to monitor andcorrect the placement of the stent in a longitudinal direction relativeto the length of the anatomical structure in which it is positioned.Once the stent is properly positioned, the balloon catheter is operatedto inflate the balloon, thus transitioning the stent to an expandedcondition.

Although the present disclosure has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A method of deploying a stented heart valveprosthesis to an implantation site, the method comprising: removablyloading a stented heart valve prosthesis to a delivery device, thedelivery device including: an inner shaft, a sheath forming a lumen anda distal region, a tubular delivery capsule having a proximal zoneattached to and extending from the distal region and a distal zoneopposite the proximal zone, wherein the stented heart valve prosthesisis coupled to the inner shaft and is slidably received within thedelivery capsule such that the delivery device retains the stented heartvalve prosthesis in a collapsed arrangement; delivering the stentedheart valve prosthesis in the collapsed arrangement through a bodilylumen and to the implantation site via the delivery device; partiallyproximally retracting the delivery capsule relative to the stented heartvalve prosthesis such that a distal portion of the stented heart valveprosthesis is exposed distal the capsule, wherein the distal portionself-expands toward an expanded arrangement and at least a proximalportion of the stented heart valve prosthesis is retained within atleast the delivery capsule in the collapsed arrangement; evaluating aposition of the stented heart valve prosthesis relative to theimplantation site; distally advancing the sheath and the capsulerelative to the stented heart valve prosthesis when the evaluationindicates that the stented heart valve prosthesis is not correctlypositioned, wherein the distal zone circumferentially flares about thestented heart valve prosthesis with the distal movement whilesimultaneously imparting a collapsing force onto a contacted region ofthe stented heart valve prosthesis, causing the contacted region totransition toward the collapsed arrangement; and fully proximallyretracting the delivery capsule from the stented heart valve prosthesissuch that the stented heart valve prosthesis deploys from the innershaft.
 2. The method of claim 1, wherein: the step of partiallyretracting the delivery capsule relative to the stented prosthetic heartvalve includes operating an actuator of the delivery device in a firstdirection; and the step of distally advancing the sheath and thedelivery capsule includes operating the actuator in a second directionopposite the first direction.
 3. The method of claim 1, wherein the stepof distally advancing the sheath and the delivery capsule includeslocating the distal zone distal the prosthetic heart valve, and furtherwherein the distal zone self-transitions from a flared state toward anormal state.
 4. The method of claim 1, wherein following the step ofdistally advancing the sheath and the delivery capsule, the methodfurther comprising repositioning the delivery capsule relative to theimplantation site with the distal zone in the normal state.